Fuel battery cell and cell stack device

ABSTRACT

A cell includes a support substrate that is of a flat plate shape that includes a first principal surface and a second principal surface on an opposite side of the first principal surface and a columnar shape that includes a longitudinal direction and includes a gas flow path in an inside thereof, and a plurality of element parts that are arranged away from one another on the first principal surface and the second principal surface where at least a fuel electrode, a solid electrolyte film, and an air electrode are laminated thereon. The cell includes a first portion that is located on a side of the first principal surface with respect to the gas flow path and a second portion that is located on a side of the second principal surface with respect to the gas flow path. Structures of the first portion and the second portion are asymmetric.

FIELD

The present invention relates to a fuel battery cell and a cell stackdevice.

BACKGROUND

A fuel battery cell has conventionally been known that includes “aporous support substrate that does not have an electron conductivitywhere a gas flow path is provided in an inside thereof”, “a plurality ofelectricity generation element parts that are respectively provided on aplurality of places that are separated from one another on a surface ofthe support substrate and are provided by laminating a fuel electrode, asolid electrolyte, and an air electrode thereon”, and “one or moreelectrical connection parts that are respectively provided between a setor plural sets of adjacent electricity generation element parts andelectrically connect a fuel electrode of one of the adjacent electricitygeneration element parts and an air electrode of another thereof” (see,for example, Patent Literature 1). Hereinafter, a fuel battery cell maysimply be referred to as a cell. Such a configuration is also called “ahorizontal stripe type”. A fuel gas is introduced from one end of a gasflow path inside such a cell and a gas that includes oxygen flows fromone end outside such a cell, so that it is possible to executeelectricity generation.

A cell stack device includes a manifold and a cell stack that is aplurality of cells (see, for example, Patent Literature 2). Each cell issupported by a manifold so as to extend upward from the manifold. A gasis distributed to each gas flow path of each cell through a manifold.

CITATION LIST Patent Literature

Patent Literature 1: Japanese Patent Application Publication No.2012-038718

Patent Literature 2: Japanese Patent Application Publication No.2017-201601

SUMMARY

A cell according to the present disclosure includes a support substratethat is of a flat plate shape that has a first principal surface and asecond principal surface on an opposite side of the first principalsurface and a columnar shape that has a longitudinal direction and has agas flow path in an inside thereof, and a plurality of element partsthat are arranged away from one another on the first principal surfaceand the second principal surface where at least a fuel electrode, asolid electrolyte, and an air electrode are laminated thereon. It has afirst portion that is located on a side of the first principal surfacewith respect to the gas flow path and a second portion that is locatedon a side of the second principal surface with respect to the gas flowpath, and structures of the first portion and the second portion areasymmetric.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1A is a perspective view that illustrates one of examples of acell.

FIG. 1B is a plan view that illustrates one of examples of a state wherea fuel electrode and an interconnector are buried in a recess thereof.

FIG. 2 is one of examples of a cross-sectional view of a cell asillustrated in FIG. 1A.

FIG. 3 is a diagram for explaining one of examples of an operationalstate of a fuel battery cell as illustrated in FIG. 1A.

FIG. 4 is one of examples of a cross-sectional view of a cell asillustrated in FIG. 1A.

FIG. 5 is a perspective view that illustrates one of examples of asupport substrate in FIG. 1A.

FIG. 6A is a cross-sectional view of FIG. 5.

FIG. 6B is a cross-sectional view that illustrates one of examples of astate where each layer is formed in a first recess in FIG. 6A.

FIG. 7 is a perspective view that illustrates one of examples of a cell.

FIG. 8 is a schematic and explanatory diagram of one of examples of acell stack device.

DESCRIPTION OF EMBODIMENTS

Hereinafter, a cell according to the present disclosure will beexplained while a fuel battery cell is provided as an example thereof.

(Fuel Battery Cell)

FIG. 1A illustrates a fuel battery cell 1 in the present embodiment. Inthe cell 1, on each of upper and lower surfaces of a support substrate10 with a columnar shape and a flat plate shape that has a longitudinaldirection in a direction of an x-axis, a plurality of electricitygeneration element parts A with an identical shape that are electricallyconnected in series are arrayed at a predetermined interval(s) in thelongitudinal direction. Upper and lower surfaces of the supportsubstrate 10 are mutually parallel principal surfaces (planar surfaces)on both sides thereof. FIG. 1A illustrates an example where it has fourelectricity generation element parts A on one of principal surfacesthereof. One of principal surfaces is provided as a first principalsurface and another of the principal surfaces is provided as a secondprincipal surface. Such a cell 1 is a so-called “horizontal stripetype”.

A shape of such a cell 1 that is viewed from above is, for example, arectangular shape where a length of a side in a longitudinal directionthereof is 5 cm to 50 cm and a length thereof in a direction of a y-axisthat is a width direction that is orthogonal to the longitudinaldirection is 1 cm to 10 cm. A thickness of such a cell 1 is 1 mm to 5mm. Hereinafter, a detail(s) of such a cell 1 will be explained withreference to FIG. 2 that is a cross-sectional view of such a cell 1 in alongitudinal direction of the cell 1 as illustrated in FIG. 1A, inaddition to FIG. 1A.

FIG. 2 is a part of a cross-sectional view of a fuel battery cell 1 asillustrated in FIG. 1A in a longitudinal direction thereof. In otherwords, it is a part of a cross-sectional view along a gas flow path(s)11.

A support substrate 10 is a fired body with a columnar shape and a flatplate shape that is composed of a porous material that does not have anelectron conductivity, that is, is of an insulation property. Inside thesupport substrate 10, gas flow paths 11 that are a plurality ofthrough-holes that extend in a longitudinal direction thereof arelocated at a predetermined interval(s) in a width direction thereof. Thesupport substrate 10 as illustrated in FIG. 2 has six gas flow paths 11.A surface that is exposed to a gas that flows through an inside of thesupport substrate 10 is provided as a gas flow path wall W.

In the present embodiment, the support substrate 10 has a first recess12 at each of a plurality of places on a principal surface thereof. Eachfirst recess 12 is a recessed portion with a rectangular solid shapethat is defined by a bottom wall that is composed of a material of thesupport substrate 10 and a side wall that is composed of a material ofthe support substrate 10 over a whole circumference thereof and isclosed in a circumferential direction thereof. A side wall that isclosed in a circumferential direction thereof is two side walls along alongitudinal direction thereof and two side walls along a widthdirection thereof. A lower principal surface in FIG. 2 is a firstprincipal surface 101 and an upper principal surface is a secondprincipal surface 102.

The support substrate 10 includes “a transition metal oxide or atransition metal” and an insulating ceramic(s). “A transition metaloxide or a transition metal” may be NiO (nickel oxide) or Ni (nickel).It is possible for a transition metal to function as a catalyst thataccelerates a reforming reaction of a fuel gas, in other words, areforming catalyst for a hydrocarbon-type gas.

An insulating ceramic(s) may be MgO (magnesium oxide) or “a mixture ofMgAl₂O₄ (magnesia alumina spinel) and MgO (magnesium oxide)”.Furthermore, CSZ (calcia-stabilized zirconia), YSZ (yttria-stablizedzirconia that may also be referred to as 8YSZ), or Y₂O₃ (yttria) may beused as an insulating ceramic(s).

The support substrate 10 includes “a transition metal oxide or atransition metal”, so that it is possible for a gas that includes aresidual gas component before reforming to accelerate reforming of sucha residual gas component before reforming by a catalytic action asdescribed above. In addition, the support substrate 10 includes aninsulating ceramic(s), so that it is possible to ensure an insulationproperty of the support substrate 10. As a result, it is possible toensure an insulation property between adjacent fuel electrodes.

A thickness of the support substrate 10 may be 1 mm to 5 mm.Hereinafter, such a structure is assumed to be substantially verticallysymmetric and only a configuration of the support substrate 10 on anupper surface side thereof will be explained for sake of simplicity ofexplanation. A lower surface side of the support substrate 10 also has asimilar configuration although a shape of a part thereof is differenttherefrom.

As illustrated in FIG. 2, a whole of a fuel electrode collector part 21fills and is buried in each first recess 12 that is located on thesecond principal surface 102 of the support substrate 10. Therefore,each fuel electrode collector part 21 is of a rectangular solid shape. Asecond recess 21 a is present on an outer surface that is an uppersurface of each fuel electrode collector part 21. As illustrated in FIG.1B, each second recess 21 a is a recessed portion with a rectangularsolid shape that is defined by a bottom wall that is composed of amaterial of the fuel electrode collector part 21 and a side wall that isclosed in a circumferential direction thereof. In a side wall that isclosed in a circumferential direction thereof, two side walls along adirection of an x-axis that is a longitudinal direction thereof areparts of the support substrate 10 and two side walls along a directionof a y-axis that is a width direction thereof are parts of the fuelelectrode collector part 21.

A fuel electrode active part 22 fills and is buried in each secondrecess 21 a. Each fuel electrode active part 22 is of a rectangularsolid shape. A fuel electrode 20 includes the fuel electrode collectorpart 21 and the fuel electrode active part 22. The fuel electrode 20,that is, the fuel electrode collector part 21 and the fuel electrodeactive part 22, is/are a porous fired body/bodies that has/have anelectron conductivity/conductivities. Two side surfaces along adirection of a y-axis that is a width direction of each fuel electrodeactive part 22 and a bottom surface contact the fuel electrode collectorpart 21 in the second recess 21 a.

A third recess 21 b is present on a part that excludes the second recess21 a on an outer surface that is an upper surface of each fuel electrodecollector part 21. Each third recess 21 b is a recessed portion with arectangular solid shape that is defined by a bottom wall that is thefuel electrode collector part 21 and a side wall that is closed in acircumferential direction thereof. In a side wall that is closed in acircumferential direction thereof, two side walls along a direction ofan x-axis that is a longitudinal direction thereof are parts of thesupport substrate 10 and two side walls along a direction of a y-axisthat is a width direction thereof are parts of the fuel electrodecollector part 21.

An interconnector 30 that is an electrically conductive dense body fillsand is buried in each third recess 21 b. Each interconnector 30 is of arectangular solid shape. The interconnector 30 is a dense fired bodythat has an electron conductivity. Two side surfaces along a widthdirection of each interconnector 30 and a bottom surface contact thefuel electrode collector part 21 in the third recess 21 b.

An outer surface(s) that is/are an upper surface(s) of the fuelelectrode 20, that is, the fuel electrode collector part 21 and the fuelelectrode active part 22, an outer surface that is an upper surface ofthe interconnector 30, and the second principal surface 102 of thesupport substrate 10 are provided in such a manner that respectivesurfaces are provided as one surface.

The fuel electrode active part 22 may include, for example, NiO (nickeloxide) and YSZ (yttria-stabilized zirconia). Alternatively, NiO (nickeloxide) and GDC (gadolinium-doped ceria) may be included therein. Thefuel electrode collector part 21 may include, for example, NiO (nickeloxide) and YSZ (yttria-stabilized zirconia). Alternatively, NiO (nickeloxide) and Y₂O₃ (yttria) may be included therein or NiO (nickel oxide)and CSZ (calcia-stabilized zirconia) may be included therein. Athickness of the fuel electrode active part 22 may be 5 μm to 30 μm. Athickness of the fuel electrode collector part 21, that is, a depth ofthe first recess 12, may be 50 μm to 500 μm.

The fuel electrode collector part 21 is of an electron conductivity. Thefuel electrode active part 22 has an electron conductivity and anoxidizing ion (an oxygen ion) conductivity. “A ratio of a volume of asubstance that has an oxidizing ion conductivity to a total volume thatexcludes a pore part” in the fuel electrode active part 22 is greaterthan “a ratio of a volume of a substance that has an oxidizing ionconductivity to a total volume that excludes a pore part” in the fuelelectrode collector part 21.

The interconnector 30 may include, for example, LaCrO₃ (lanthanumchromite). Alternatively, (Sr,La)TiO₃ (strontium titanate) may beincluded therein. A thickness of the interconnector 30 may be 10 μm to100 μm. A porosity thereof may be 10% or less.

On an outer peripheral surface of the support substrate 10 that extendsin an array direction of electricity generation element parts A that isa longitudinal direction thereof, a whole surface of a plurality ofinterconnectors 30 that excludes a central part thereof may be coveredby a solid electrolyte film 40. The solid electrolyte film 40 is a densefired body that has an ion conductivity and does not have an electronconductivity. The solid electrolyte film 40 may include, for example,YSZ (yttria-stabilized zirconia). Alternatively, LSGM (lanthanumgallate) may be included therein. A thickness of the solid electrolytefilm 40 may be 3 μm to 50 μm.

A whole surface of an outer peripheral surface of the support substrate10 that extends in a longitudinal direction thereof may be covered by adense layer that is composed of the interconnector 30 and the solidelectrolyte film 40. Such a dense layer has a gas seal function toprevent a fuel gas that flows through an inner space of the dense layerand air that flows through an outer space of the dense layer from beingreadily mixed.

As illustrated in FIG. 2, in the present embodiment, the solidelectrolyte film 40 covers an upper surface(s) of the fuel electrode 20that is the fuel electrode collector part 21 and the fuel electrodeactive part 22, both end parts of an upper surface of the interconnector30 in a longitudinal direction thereof, and a principal surface of thesupport substrate 10.

An air electrode 60 is located on an upper surface of the solidelectrolyte film 40 at a place where it contacts each fuel electrodeactive part 22, through a non-illustrated reaction prevention film. Areaction prevention film is a dense fired body. The air electrode 60 isa porous fired body that has an electron conductivity. Shapes of areaction prevention film and the air electrode 60 that are viewed fromabove are rectangular shapes that are substantially identical to that ofthe fuel electrode active part 22.

A reaction prevention film may include, for example, (Ce,Gd)O₂(gadolinium-doped ceria, GDC). A thickness of a reaction prevention filmmay be 3 μm to 50 μm. The air electrode 60 may include, for example,(La,Sr) (Co,Fe)O₃ (lanthanum strontium cobalt ferrite, LSCF). The airelectrode 60 may include (La,Sr)FeO₃ (lanthanum strontium ferrite, LSF),La(Ni,Fe)O₃ (lanthanum nickel ferrite, LNF), (La,Sr)CoO₃ (lanthanumstrontium cobaltite, LSC), or the like. The air electrode 60 may have atwo-layer structure that is a first layer that is an inner layer that iscomposed of LSCF and a second layer that is an outer layer that iscomposed of LSC. A thickness of the air electrode 60 may be 10 μm to 100μm.

As a reaction prevention film is interposed therebetween, YSZ in thesolid electrolyte film 40 and Sr in the air electrode 60 is preventedfrom readily reacting at a time of cell fabrication or in a cell duringan operation thereof, so that a reaction layer with a high electricalresistance is prevented from being readily formed at an interfacebetween the solid electrolyte film 40 and the air electrode 60.

As illustrated in FIG. 2, a laminated body where the fuel electrode 20,the solid electrolyte film 40, and the air electrode 60 are laminatedcorresponds to “an electricity generation element part A”. Anelectricity generation element part A may include a reaction preventionfilm. A plurality of (four, in the present embodiment) electricitygeneration element parts A are arranged on a second principal surface ofthe support substrate 10 at a predetermined interval(s) in alongitudinal direction thereof.

Between adjacent electricity generation element parts A, an airelectrode collector part 70 is located on upper surfaces of the airelectrode 60, the solid electrolyte film 40, and the interconnector 30so as to bridge over the air electrode 60 of an electricity generationelement part A and the interconnector 30. The air electrode collectorpart 70 is a porous fired body that has an electron conductivity. Ashape of the air electrode collector part 70 that is viewed from aboveis a rectangular shape.

For example, the air electrode collector part 70 may include (La,Sr)(Co,Fe)O₃ (lanthanum strontium cobalt ferrite, LSCF) or may include(La,Sr)CoO₃ (lanthanum strontium cobaltite, LSC). Furthermore, the airelectrode collector part 70 may include Ag (silver) or Ag—Pd (a silverpalladium alloy). A thickness of the air electrode collector part 70 maybe 50 μm to 500 μm. A porosity of the air electrode collector part 70may be 20 to 60%.

Adjacent electricity generation element parts A are electricallyconnected through “an air electrode collector part 70 and aninterconnector 30” that have electron conductivities. A plurality of(four, in the present embodiment) electricity generation element parts Athat are arranged on an upper surface of the support substrate 10 areelectrically connected in series. A part other than “electricitygeneration element parts A” that include “an air electrode collectorpart 70 and an interconnector 30” that have electron conductivities isprovided as “an electrical connection part B”.

A side of the gas flow path(s) 11 of the support substrate 10 may beprovided as “an inner side” and a side of a surface of the supportsubstrate 10 where an electricity generation element part(s) A is/arearranged may be provided as “an outer side”.

As illustrated in FIG. 3, a fuel gas such as a hydrogen gas flowsthrough a gas flow path(s) 11 of a support substrate 10 from a first endthat is one end of the support substrate 10 in a longitudinal directionthereof to a second end that is another end thereof, and “a gas thatincludes oxygen” such as air flows along upper and lower surfaces of thesupport substrate 10, in particular, each air electrode collector part70, from the first end to the second end, so that an electromotive forceis generated by an oxygen partial pressure difference that is causedbetween both side surfaces of a solid electrolyte film 40. Moreover, assuch a structural body is connected to an external load, chemicalreactions as indicated by formulas (1) and (2) as described below occur,so that a current flows to provide an electricity generation state.

(1/2).O₂+2e ⁻→O²⁻ (at: an air electrode 60)  (1)

H₂+O²⁻→H₂O+2e ⁻ (at: a fuel electrode 20)  (2)

In an electricity generation state, as illustrated in FIG. 2, a currentflows between adjacent electricity generation element parts A asindicated by a thick arrow. As a result, an electric power is taken froma whole of the cell 1. Specifically, an electric power is taken throughan interconnector 30 of an electricity generation element part A on aforemost side in FIG. 3 and an air electrode 60 of an electricitygeneration element part A on an innermost side therein. Each cell 1 mayhave a collector member for electrically connecting a front side and aback side thereof in series.

Meanwhile, in a case where a cell stack is fabricated where a pluralityof cells 1 are combined, a temperature environment may be differentbetween both sides of a cell 1. Accordingly, a reaction rate isdifferent between a side of one principal surface and a side of anotherprincipal surface, so that a part where local degradation readilyprogresses is produced. That is, a durability of the cell 1 may belowered.

The cell 1 according to the present disclosure has a first portion 1 athat is located on a side of the first principal surface 101 withrespect to the gas flow path(s) 11 and a second portion 1 b that islocated on a side of the second principal surface 102 with respect tothe gas flow path(s) 11, and structures of the first portion 1 a and thesecond portion 1 b are asymmetric.

As one of examples where structures of the first portion 1 a and thesecond portion 1 b are asymmetric, a total length of a gas flow pathwall W in a cross-sectional view along the gas flow path(s) 11 of thesupport substrate 10 may be different between the first portion 1 a on aside of the first principal surface 101 that is located on a lower sideof FIG. 2 and the second portion 1 b on a side of the second principalsurface 102 that is located on an upper side of FIG. 2, like anembodiment as illustrated in FIG. 2. In the present embodiment, a totallength of a gas flow path wall W2 on a side of the second principalsurface 102 is less than a total length of a gas flow path wall W1 on aside of the first principal surface 101.

In a case where a cell stack is provided where a plurality of cells 1are combined, it is possible to arrange a cell 1 in such a manner thatthe second principal surface 102 where a total length of the gas flowpath wall W2 is small faces a high temperature side and the firstprincipal surface 101 where a total length of the gas flow path wall W1is large faces a low temperature side. As the first principal surface101 faces a low temperature side where a reaction as described abovedoes not readily occur, it is possible to increase a probability that afuel gas collides with the gas flow path wall W1 on a side of the firstprincipal surface 101, so that such a fuel gas is readily introducedinto the support substrate 10 and a reaction as described above readilyoccurs on the low temperature side. As the second principal surface 102faces a high temperature side where a reaction readily occurs, it ispossible to decrease a probability that a fuel gas collides with the gasflow path wall W2 on a side of the second principal surface 102, so thatsuch a fuel gas is not readily introduced into a support substrate and areaction as described above does not readily occur on the hightemperature side. Therefore, a part where local degradation readilyprogresses is not readily produced, so that a durability of a whole cellis not readily lowered.

In an embodiment of FIG. 2, the gas flow path wall W on a side of thefirst principal surface 101 is of a wavy shape in a cross-sectional viewas described above. In such a configuration, it is possible to increasea probability that a fuel gas collides with the gas flow path wall W1 ona side of the first principal surface 101, so that such a fuel gas isreadily introduced into the support substrate 10 and a reaction asdescribed above readily occurs on a low temperature side. Additionally,the gas flow path wall W2 on a side of the second principal surface 102may also be of a wavy shape similarly, like the present embodiment. Awavy shape means that the gas flow path wall W is of a snaking shape ina cross-sectional view as described above.

It is possible to calculate a total length of the gas flow path wall Wby measuring a length of the gas flow path wall W in a photograph of across section along the gas flow path(s) 11 as illustrated in FIG. 2. Atotal length of the gas flow path wall W is not a length of a straightline in a direction where the gas flow path(s) 11 extend(s) but means alength along the gas flow path wall W. In an embodiment of FIG. 2, thegas flow path wall W1 on a side of the first principal surface 101 is ofa wavy shape that snakes more greatly than that of the gas flow pathwall W2 on a side of the second principal surface 102, so that a totallength of the gas flow path wall W1 on a side of the first principalsurface 101 is greater than a total length of the gas flow path wall W2on a side of the second principal surface 102.

Additionally, although the gas flow path wall W1 on a side of the firstprincipal surface 101 is of a wavy shape in the present embodiment, itmay be, for example, an arc shape.

A total length of the gas flow path wall W1 on a side of the firstprincipal surface 101 may be greater than a total length of the gas flowpath wall W that is located midway between the first principal surface101 and the second principal surface 102. In such a configuration, it ispossible to introduce a lot of a fuel gas from the gas flow path wall W1that is close to the first principal surface 101, so that a reaction asdescribed above readily occurs on a side of the first principal surface101. It is possible to specify a total length of the gas flow path wallW that is located midway between the first principal surface 101 and thesecond principal surface 102 from a cross section along the gas flowpath(s) 11 in a direction that is orthogonal to a cross section in FIG.2 (a cross section that is parallel to each principal surface and alongthe gas flow path(s) 11). A total length of the gas flow path wall W2 ona side of the second principal surface 102 may be greater than a totallength of the gas flow path wall W that is located midway between thefirst principal surface 101 and the second principal surface 102.

In an embodiment of FIG. 2, in a cross-sectional view along the gas flowpath(s) 11 of the support substrate 10, a sum of a length of aninterface between the fuel electrode 20 and a solid electrolyte 40 forrespective electricity generation element parts A on a side of the firstprincipal surface 101 and a sum of a length of an interface between thefuel electrode 20 and the solid electrolyte 40 for respectiveelectricity generation element parts A on a side of the second principalsurface 102 may be different. In the present embodiment, a sum of alength of an interface between the fuel electrode 20 and the solidelectrolyte 40 for respective electricity generation element parts A ona side of the second principal surface 102 is less than a sum of alength of an interface between the fuel electrode 20 and the solidelectrolyte 40 for respective electricity generation element parts A ona side of the first principal surface 101.

In a case where a cell stack is provided where a plurality of cells 1are combined, it is possible to arrange a cell 1 in such a manner thatthe second principal surface 102 where a sum of a length of an interfacebetween the fuel electrode 20 and the solid electrolyte 40 is smallfaces a high temperature side and the first principal surface 101 wherea sum of a length of an interface between the fuel electrode 20 and thesolid electrolyte 40 is large faces a low temperature side. Also in sucha configuration, a part where local degradation readily progresses isnot readily produced, so that a durability of a whole of the cell 1 isnot readily lowered.

A sum of a length of an interface between the fuel electrode 20 and thesolid electrolyte 40 on a side of the first principal surface 101 is avalue provided by measuring a length of an interface between the fuelelectrode 20 and the solid electrolyte 40 for respective electricitygeneration element parts A on a side of the first principal surface 101based on a photograph of a cross section along the gas flow path(s) 11as illustrated in FIG. 2 and adding respective lengths. Also, a sum of alength of an interface between the fuel electrode 20 and the solidelectrolyte 40 on a side of the second principal surface 102 is similarthereto. A length of an interface between the fuel electrode 20 and thesolid electrolyte 40 is not a length of a straight line in a directionwhere the gas flow path(s) 11 extend(s) but means a length along such aninterface. In an embodiment of FIG. 2, an interface on a side of thefirst principal surface 101 is of a shape that greatly protrudes to aside of a gas flow path with respect to an interface on a side of thesecond principal surface 102, so that a length of an interface on a sideof the first principal surface 101 is greater than a length of aninterface on a side of the second principal surface 102.

Additionally, although FIG. 2 illustrates an example where a totallength of the gas flow path wall W1 on the first portion 1 a and a totallength of the gas flow path wall W2 on the second portion 1 b aredifferent and a sum of a length of an interface between the fuelelectrode 20 and the solid electrolyte 40 on a side of the firstprincipal surface 101 and a sum of a length of an interface between thefuel electrode 20 and the solid electrolyte 40 on a side of the secondprincipal surface 102 are different, only one of a total length of aflow path wall and a sum of a length of an interface between the fuelelectrode 20 and the solid electrolyte 40 may be different between thefirst portion 1 a and the second portion 1 b.

For one of examples where structures of a first portion 1 a and a secondportion 1 b are asymmetric, a porosity of a support substrate 10 on thefirst portion 1 a and a porosity of the support substrate 10 on thesecond portion 1 b may be different, like an embodiment as illustratedin FIG. 4. In the present embodiment, a porosity of a support substrate10 on the second portion 1 b that is located on a lower side of FIG. 4is less than a porosity of the support substrate 10 on the first portion1 a that is located on an upper side of FIG. 4.

Additionally, in FIG. 4, a first principal surface 101 of the supportsubstrate 10 is located on an upper side thereof and a second principalsurface 102 of the support substrate 10 is located on a lower sidethereof. FIG. 4 illustrates a pore 10 c inside the support substrate 10.

In a case where a cell stack is provided where a plurality of cells 1are combined, it is possible to arrange a cell 1 in such a manner that asecond principal surface 102 that is a low porosity side faces a hightemperature side and a first principal surface 101 that is a highporosity side faces a low temperature side. A porosity of the supportsubstrate 10 on a side of the first principal surface 101 is higher thana porosity of the support substrate 10 on a side of the second principalsurface 102, so that a fuel gas penetrates into the support substrate 10and readily reaches a fuel electrode 20 on a side of the first principalsurface 101 and eventually a reaction as described above readily occursat an electricity generation element part A on a side of the firstprincipal surface 101. That is, the first principal surface 101 of thesupport substrate 10 faces a low temperature side where a reaction doesnot readily occur, so that a reaction as described above readily occurs.The second principal surface 102 faces a high temperature side where areaction readily occurs, so that a reaction as described above does notreadily occur on the high temperature side. Therefore, a part wherelocal degradation readily progresses is not readily produced, so that adurability of a whole cell is not readily lowered.

It is possible to analyze a porosity of the support substrate 10 by amethod as described later. First, three dividing lines are drawn in alongitudinal direction of the support substrate 10, that is, along a gasflow path(s) 11 in such a manner that a length of the support substrate10 in a width direction thereof is divided into four equal parts. Then,gas flow paths 11 that are closest to respective dividing lines in awidth direction thereof are specified respectively. Then, three crosssections of the support substrate 10 that include three respective gasflow paths 11 that are specified are obtained. Then, an image in anobtained cross section is acquired by a scanning electron microscope.Then, a binarization process is executed in such a manner that it ispossible to distinguish between a part that is the pore 10 c and a partthat is not the pore 10 c in an acquired image. Then, in each crosssection, a proportion of the pore 10 c in a region of the supportsubstrate 10 on a side of the first principal surface 101 and aproportion of the pore 10 c in a region of the support substrate 10 on aside of the second principal surface 102 are calculated. Then, anaverage porosity of the support substrate 10 on the first portion 1 aand an average porosity of the support substrate 10 on the secondportion 1 b are calculated from a proportion of the pore 10 c that iscalculated in each cross section.

A method for adjusting porosities of the support substrate 10 on a sideof the first principal surface 101 and a side of the second principalsurface 102 will be explained. As one method, it is possible to attainrealization by applying a sintering aid to a surface of the secondprincipal surface 102 of a molded body for a support substrate 10 g andsubsequently executing firing thereof. The support substrate 10 on aside of the second principal surface 102 is more dense than that on aside of the first principal surface 101, that is, it is possible toprovide a porosity of the support substrate 10 on a side of the secondprincipal surface 102 that is less than that of the support substrate 10on a side of the first principal surface 101.

Like an embodiment of FIG. 4, a length from the gas flow path(s) 11 ofthe support substrate 10 to the first principal surface 101 and a lengthfrom the gas flow path(s) 11 to the second principal surface 102 may bedifferent. In the present embodiment, a length from the gas flow path(s)11 of the support substrate 10 to the second principal surface 102 isgreater than a length from the gas flow path(s) 11 to the firstprincipal surface 101.

That is, in a case where a cell stack is provided where a plurality ofcells 1 are combined, it is possible to arrange a cell 1 in such amanner that the second principal surface 102 faces a high temperatureside and the first principal surface 101 faces a low temperature side. Alength of the support substrate 10 from the gas flow path(s) 11 to thefirst principal surface 101 is less than a length of the supportsubstrate 10 from the gas flow path(s) 11 to the second principalsurface 102, so that a fuel gas readily penetrates into the supportsubstrate 10 so as to reach the fuel electrode 20 on a side of the firstprincipal surface 101 and eventually a reaction as described abovereadily occurs at an electricity generation element part A on a side ofthe first principal surface 101. That is, the first principal surface101 of the support substrate 10 faces a low temperature side where areaction does not readily occur, so that a reaction as described abovereadily occurs. The second principal surface 102 faces a hightemperature side where a reaction readily occurs, so that a reaction asdescribed above does not readily occur on the high temperature side.Therefore, a part where local degradation readily progresses is notreadily produced, so that a durability of a whole cell is not readilylowered.

It is possible to analyze a length from the gas flow path(s) 11 to thefirst principal surface 101 and a length from the gas flow path(s) 11 tothe second principal surface 102 by a method as described later. First,three dividing lines are drawn in a longitudinal direction of thesupport substrate 10, that is, along the gas flow path(s) 11, in such amanner that a length of the support substrate 10 in a width directionthereof is divided into four equal parts. Then, respective gas flowpaths 11 that are closest to respective dividing lines in a widthdirection thereof are specified. Then, three cross sections of thesupport substrate 10 that include three respective gas flow paths 11that are specified are obtained. Then, an image in an obtained crosssection is acquired by a scanning electron microscope. Then, a region ofthe support substrate 10 that includes the pore 10 c in an acquiredimage is specified. Then, in each cross section, a value of a surfacearea of a region of the support substrate 10 on a side of the firstprincipal surface 101 and a value of a surface area of a region of thesupport substrate 10 on a side of the second principal surface 102 arecalculated. Then, an average surface area value of the support substrate10 on the first portion 1 a and an average surface area value of thesupport substrate 10 on the second portion 1 b are calculated from avalue that is calculated in each cross section. A ratio of an averagesurface area value of the support substrate 10 on the first portion 1 aand an average surface area value of the support substrate 10 on thesecond portion 1 b is regarded as a ratio of lengths from the gas flowpath(s) 11 of the support substrate 10 to respective principal surfaces.

Additionally, although FIG. 4 illustrates an example where a porosity ofthe support substrate 10 on the first portion 1 a and a porosity of thesupport substrate 10 on the second portion 1 b are different and alength from the gas flow path(s) 11 to the first principal surface 101and a length from the gas flow path(s) 11 to the second principalsurface 102 are different, only one of a porosity of the supportsubstrate 10 and a length from the gas flow path(s) 11 to a principalsurface may be different between the first portion 1 a and the secondportion 1 b.

In a case where a cell 1 has a first electricity generation element partA1 on the first principal surface 101 of the support substrate 10 with aflat plate shape and has a second electricity generation element part A2on the second principal surface 102 thereof, the first electricitygeneration element part A1 and the second electricity generation elementpart A2 may be arranged at asymmetric positions. That is, the firstelectricity generation element part A1 and the second electricitygeneration element part A2 do not have to be arranged at symmetricpositions.

Next, an example of a manufacturing method for a “horizontal stripetype” cell 1 as illustrated in FIG. 1 will simply be explained withreference to FIG. 5, FIG. 6A, and FIG. 6B. In FIG. 5, FIG. 6A, and FIG.6B, “g” at an end of a sign for each member indicates that such a memberis “before firing”.

First, a molded body for a support substrate 10 g that has a shape asillustrated in FIG. 5 is fabricated. It is possible to fabricate such amolded body for a support substrate 10 g by, for example, using a slurrythat is obtained by adding a binder or the like to a powder thatincludes a material of a support substrate 10, for example, NiO and MgO,and utilizing a technique such as extrusion molding or cutting.

A method for providing a shape of a gas flow path wall of the supportsubstrate 10 as a wavy shape will be explained below. As one method,when the molded body for a support substrate 10 g is fabricated byextrusion molding, it is also possible to attain realization bypreparing and extrusion-molding a material of the molded body for asupport substrate 10 g that has a desired density difference by using aso-called plunger extruder. That is, sintering is comparatively readilyexecuted at a high density part, so that further contraction toward aninside thereof is caused at such a part and a gas flow path wall surface13 of a gas flow path further approaches an inside thereof. On the otherhand, in a case where a density is comparatively low, sintering is notcomparatively readily executed and the gas flow path wall surface 13 ofa gas flow path approaches a comparatively outer side.

Then, as illustrated in FIG. 6B, a molded body for a fuel electrodecollector part 21 g is arranged in each of respective first recessesthat are formed on upper and lower surfaces of the molded body for asupport substrate 10 g. Then, a molded body for a fuel electrode activepart 22 g is arranged in each of respective second recesses that areformed on outer surfaces of each molded body for a fuel electrodecollector part 21 g. Furthermore, each molded body for a fuel electrodecollector part 21 g and each fuel electrode active part 22 g arearranged by, for example, using a slurry that is obtained by adding abinder or the like to a powder that includes a material of a fuelelectrode 20, for example, Ni and YSZ, and utilizing a printing methodor the like.

Subsequently, a molded body for an interconnector 30 g is arranged ineach of respective third recesses that are formed on “a part thatexcludes a part where a molded body for a fuel electrode active part 22g is buried” on outer surfaces of each molded body for a fuel electrodecollector part 21 g. Each molded body for an interconnector 30 g isarranged by, for example, using a slurry that is obtained by adding abinder or the like to a powder of a material of an interconnector 30,for example, LaCrO₃, and utilizing a printing method or the like.

Then, a molded film for a solid electrolyte film is provided on a wholesurface that excludes central parts of respective parts where theplurality of molded bodies for an interconnector 30 g are arranged, onan outer peripheral surface of the molded body for a support substrate10 g that extends in a longitudinal direction thereof. For a molded filmfor a solid electrolyte film, for example, a slurry that is obtained byadding a binder or the like to a powder of a material of a solidelectrolyte film 40, for example, YSZ, is used and a printing method, adipping method, or the like is utilized.

Then, a molded film for a reaction prevention film is provided on anouter surface of a molded body for a solid electrolyte film at a placewhere it contacts each molded body for a fuel electrode. For each moldedfilm for a reaction prevention film, for example, a slurry that isobtained by adding a binder or the like to a powder of a material of areaction prevention film, for example, GDC, is used and a printingmethod or the like is utilized.

Then, the molded body for a support substrate 10 g in a state where avariety of molded films are thus provided is fired. Herein, as atemperature of a side of a first principal surface 101 is higher thanthat of a side of a second principal surface 102, the support substrate10 at a high density part on a side of the first principal surface 101is sintered more readily, so that further contraction toward an insidethereof is caused at such a part and the gas flow path wall surface 13of the gas flow path 11 further approaches an inner side. Thereby, it ispossible to provide a gas flow path wall W1 on a side of the firstprincipal surface 101 with a wavy shape that greatly snakes from a gasflow path wall W2 on a side of the second principal surface 102. Forexample, while a side of the first principal surface 101 is provided at1500° C. and a side of the second principal surface 102 is provided at1450° C., firing is executed for 3 hours. Furthermore, a part of aninterface between the fuel electrode 20 and the solid electrolyte 40also protrudes to a side of the gas flow path(s) 11 according to shapedeformation that is caused by sintering of the support substrate 10.

Additionally, in a case where it is desired that a shape is provided insuch a manner that a part of an interface between the fuel electrode 20and the solid electrolyte 40 also protrudes to a side of a gas flowpath, it is also possible to attain realization by fabricating a moldedbody that has such a shape.

Then, a molded film for an air electrode is formed on an outer surfaceof each reaction prevention film. Each molded film for an air electrodeis provided by, for example, using a slurry that is obtained by adding abinder or the like to a powder of a material of an air electrode 60, forexample, LSCF, and utilizing a printing method or the like.

Then, for each set of adjacent electricity generation element parts A, amolded film for an air electrode collector part is provided on outersurfaces of a molded film for an air electrode, the solid electrolytefilm 40, and the interconnector 30 so as to bridge over a molded filmfor an air electrode of one of the electricity generation element partsA and the interconnector 30 of another of the electricity generationelement parts A.

It is possible to provide a molded film for an air electrode collectorpart that is provided with a desired shape (thickness), on an outersurface of a molded film for an air electrode or the like, by using aslurry that is obtained by adding a binder or the like to a powder of amaterial of an air electrode collector part 70, for example, LSCF, andby a printing method or the like.

Then, the support substrate 10 in a state where molded films are thusformed is fired, for example, in air at 1050° C. for 3 hours. Thereby, acell as illustrated in FIG. 1 is obtained.

Additionally, as illustrated in FIG. 7, on at least one principalsurface among the first principal surface 101 and the second principalsurface 102, at least one electricity generation element part A among aplurality of electricity generation element parts A that are arrayed ina longitudinal direction thereof, that is, a direction of an x-axis, maybe arranged at a position that is different from that of anotherelectricity generation element part A in a direction that is orthogonalto a direction where the plurality of electricity generation elementparts A are arrayed on such a principal surface. In other words, on atleast one principal surface among the first principal surface 101 andthe second principal surface 102, a position of at least one electricitygeneration element part A among a plurality of electricity generationelement parts A in a width direction thereof, that is, a direction of ay-axis, may be shifted from another electricity generation element partA. Respective positions of a plurality of electricity generation elementparts A in a direction of a y-axis may be different.

In general, a temperature of an electricity generation element part Awhere a reaction as described above occurs is comparatively high. Hence,as electricity generation element parts A are arrayed along a centralpart of the support substrate 10 in a width direction thereof, atemperature of a central part of a cell 1 in a width direction thereofis particularly high. A position of at least one electricity generationelement part A in a width direction thereof is shifted from that ofanother electricity generation element part A, so that a deviation of atemperature distribution in the width direction is not readily caused.Eventually, a part where local degradation readily progresses is notreadily produced and a durability of a whole of a cell 1 is not readilylowered.

(Cell Stack Device)

FIG. 8 is a schematic and explanatory diagram of a cell stack device. Acell stack device 80 in FIG. 8 includes a cell stack 81 and a fixingmember 82. The cell stack 81 has a plurality of cells 1 and a pluralityof cells 1 are respectively arrayed in a direction where both principalsurfaces of a support substrate 10 are opposed. The fixing member 82 isa member that fixes one end side of a cell 1 in a longitudinal directionthereof. The fixing member 82 has a gas storage space for storing a fuelgas that is supplied to a gas flow path(s) 11 of the cell 1, in aninside thereof. The cell stack device 80 includes a fuel gas supply pipe83 for supplying a fuel gas to a gas storage space.

A connection member 84 with a comb teeth shape is arranged betweenrespective cells 1. In such a cell stack device 80, it is possible toelectrically connect all arrayed cells 1 in series by the connectionmember 84, so that it is possible to obtain a desired amount of electricpower generation efficiently. It is sufficient that a number of acell(s) 1 is appropriately adjusted depending on a desired amount ofelectric power generation.

Each cell 1 is fixed to the fixing member 82 by, for example, anadhesive with an insulation property such as, for example, glass. It issufficient that the fixing member 82 is fabricated by a material thathas a heat resistance, so that it is possible to execute fabricationwith, for example, a material such as a metal that is composed ofsilicon, iron, titanium oxide, aluminum oxide, or the like or aceramic(s) that has/have a heat resistance.

Meanwhile, in a case where a plurality of cells 1 are arranged incolumn, like the cell stack 81 of the cell stack device 80 asillustrated in FIG. 8, a temperature at a center of the cell stack 81 inan array direction of a cell 1, that is, a direction of a z-axis iscomparatively high. Hence, in a case where the cell stack device 80 asillustrated in FIG. 8 is assembled by using a cell 1 in an embodiment asillustrated in FIG. 2 and FIG. 4, it is possible to arrange cells 1 insuch a manner that a second principal surface 102 faces a side where acenter 81C of the cell stack 81 in array direction thereof is located,that is, a first principal surface 101 faces a side that is opposite toa side where a center of the cell stack 81 is located. As such aconfiguration is provided, a part where local degradation readilyprogresses is not readily produced and a durability of a whole of a cell1 is not readily lowered.

As illustrated in FIG. 8, for example, the second principal surface 102of a cell 1 that is located so as to be leftmost in the cell stack 81faces a side where a cell stack center 81C is located, in other words,the first principal surface 101 of such a cell 1 faces an opposite sideof a side where the cell stack center 81C is located.

(Fuel Battery Module)

A fuel battery module according to the present invention is configuredto house the cell stack device 80 as described above in a housingcontainer. Thereby, it is possible to provide a fuel battery module witha high durability.

Additionally, the present invention is not limited to an embodiment(s)as described above and a variety of improvements or modifications arepossible within a scope as described in the claim(s). For example,although an embodiment as described above is explained by using a cellthat is called a so-called horizontal stripe type, it is also possibleto use a vertical stripe type cell that is provided by providing aplurality of electricity generation element parts that are called avertical stripe type in general on a support substrate. Furthermore,although a fuel battery cell, a fuel battery cell stack device, a fuelbattery module, and a fuel battery device are illustrated as one ofexamples of a “cell”, a “cell stack device”, a “module”, and a “modulehousing device” in an explanation as described above, an electrolysiscell, an electrolysis cell stack device, an electrolysis module, and anelectrolysis device may respectively be provided as another examplethereof.

REFERENCE SIGNS LIST

-   1 . . . cell-   1 a . . . first portion    -   1 b . . . second portion-   A . . . element part-   B . . . electrical connection part-   10 . . . support substrate-   101 . . . first principal surface-   102 . . . second principal surface-   11 . . . gas flow path-   W . . . gas flow path wall-   20 . . . fuel electrode-   40 . . . solid electrolyte-   60 . . . air electrode-   70 . . . air electrode collector part-   80 . . . cell stack device-   81 . . . cell stack-   81C . . . cell stack center-   82 . . . fixing member

1. A cell, comprising: a support substrate including: a first surface; asecond surface opposite to the first surface; and a gas flow pathbetween the first surface and the second surface; a first element partlaminated on the first surface, the first element part including atleast a first fuel electrode, a first solid electrolyte film, and afirst air electrode; and a second element part laminated on the secondsurface, the second element part including at least a second fuelelectrode, a second solid electrolyte film, and a second air electrode,wherein a first portion that includes the first element part and aportion of the support substrate that is located on a side of the firstsurface with respect to the gas flow path is asymmetric to a secondportion that includes the second element part and another portion of thesupport substrate that is located on a side of the second surface withrespect to the gas flow path.
 2. The cell according to claim 1, whereina total length of a gas flow path wall of the second portion is lessthan a total length of a gas flow path wall of the first portion, in across-sectional view of the support substrate along the gas flow path.3. The cell according to claim 2, wherein the gas flow path wall of thefirst portion is of a wavy shape in the cross-sectional view.
 4. Thecell according to claim 1, wherein a length of an interface between thesecond fuel electrode and the second solid electrolyte film is less thana length of an interface between the first fuel electrode and the firstsolid electrolyte film, in a cross-sectional view of the supportsubstrate along the gas flow path.
 5. The cell according to claim 1,wherein a porosity of the other portion of the support substrate of thesecond portion is less than a porosity of the portion of the supportsubstrate of the first portion.
 6. The cell according to claim 1,wherein a length of the support substrate from the gas flow path to thesecond surface is greater than a length of the support substrate fromthe gas flow path to the first surface.
 7. The cell according to claim1, wherein: the first element part includes a first element, and asecond element arranged along the gas flow path with the first elementand separated from the first element; and the cell includes a connectorbetween the first element and the second element that electricallyconnects the first fuel electrode of the first element and the first airelectrode of the second element.
 8. The cell according to claim 7,wherein the second element is arranged at a position different from thefirst element in a direction orthogonal to the gas flow path.
 9. A cellstack device, comprising: a cell stack where a plurality of the cellsaccording to claim 1 are arrayed, and a fixing member that fixes one endside of the plurality of cells in a direction in which the gas flow pathextends in the cell stack.
 10. A cell stack device, comprising: a cellstack where a plurality of the cells according to claim 2 are arrayed ina direction, and a fixing member that fixes one end side of theplurality of cells in a direction in which the gas flow path extends inthe cell stack, wherein the second surface of at least one of theplurality of cells faces a center of the cell stack.